Current space telescopes, such as the Hubble Space Telescope Imaging Satellite shown in FIG. 3, include a primary mirror (also referred to as an aperture) and a secondary mirror encapsulated within cylindrical barrel assembly 205. An exposed end 208 of the tubular outer barrel assembly permits the entrance of light that is reflected and focused by the mirrors. The open end of the outer barrel assembly may be commonly referred to as an opening 208. The outer barrel assembly 205 shields the mirrors from the heat of the sun, protects the mirrors from space debris, and limits the exposure of the mirrors to stray light, i.e. light not emanating from the point of observation. Stray light decreases the signal to noise ratio (SNR) of the telescope thereby degrading the image quality of the telescope.
A cover 210 is pivotably coupled to open end 208 of outer barrel assembly 205. In an open arrangement, cover 210 is separated from the opening, permitting light to enter the outer barrel assembly, so that the telescope can collect images. In a closed arrangement, cover 210 conceals opening 208, thereby restricting the introduction of light and/or space debris into the outer barrel assembly. The cover 210 is closed during the launch of the satellite and periods when the telescope is not actively collecting images in order to conserve thermal energy and conceal the mirrors from direct sun rays.
The conventional covers are heavy, consume space in the launch vehicle, and have a large moment of inertia which can reduce deployment speed. Moreover, the spatial envelope consumed by the pivoting cover extends beyond the radial boundaries of the outer barrel assembly. In a testing environment (prior to launch), a telescope is positioned in a test tower for testing and analysis of the telescope. However, a conventional test tower may not permit deployment of the cover, due to vertical and radial space constraints, consequently preventing any functional optical test of the telescope in the test chamber. In addition to the above, the outer barrel assembly must be sufficiently robust to support the weight and pivoting action of the cover.
There is a need to further develop and refine outer barrel assemblies and covers to solve the physical space and weight constraints of the telescope.